Field of the Invention
The present invention relates to an image pickup apparatus including an image pickup element, and more particularly relates to an image pickup apparatus including an image pickup element including a plurality of sub pixels for each pixel.
Description of the Related Art
A recent image pickup apparatus including an image pickup element such as a CMOS sensor has multi-functionality, and not only generates a shot image such as a still image or a moving image but also performs control, such as focusing, of the image pickup apparatus based on object information obtained by the image pickup element.
Japanese Patent Laid-open No. 2001-124984 discloses a configuration capable of performing focus detection by a pupil division method using a signal obtained from an image pickup element. Japanese Patent Laid-open No. 2001-124984 discloses a configuration in which one micro lens and two photodiodes are provided for each pixel of the image pickup element, the photodiodes being configured to receive lights passing through different pupil regions of a image pickup lens. Such a configuration allows focus detection by comparing output signals from the two photodiodes and generation of a shot image by adding the output signals from the two photodiodes.
The image pickup element such as a CMOS sensor needs corrections such as an offset correction and a gain correction for each pixel (or, for each pixel column, or for each pixel row) to remove fixed pattern noise caused by a signal readout circuit of the image pickup element.
However, in a case with a plurality of photodiodes provided for each pixel, as disclosed by Japanese Patent Laid-open No. 2001-124984, performing corrections for each photodiode results in an increased amount of correction data, which requires a large amount of memory.